USLight2013 via eBay offers the 7-watt LED Light Bulb 10-Pack in Warm or White for $29 with free shipping. That's $2.90 per bulb and $29 under the lowest total price we could find for a similar 10-pack sold elsewhere. They feature up to 650 lumens of brightness.
Need even more bulbs? Also available is a 20-Pack for $57 or a 30-Pack for $81.
Update: Specs corrected.